The subject invention provides for new and improved resilient rail fastener assemblies for fastening rails on curved tracks. The rail fastener assembly includes a unitary base plate having an upstanding resilient seat retaining shoulder disposed on one end of the base, and a pair of spaced, generally planar parallel upstanding rail brace plates welded to the base plate, on the opposed end thereof. The load carrying rail is received in the base with an elastomeric pad interposed between the rail and the base with the pad acting as a resilient seat. In a single superelevated rail installation, the brace plates are disposed in abutting relationship with the upper portion of the rail such that centrifugal forces imparted to the rail by rolling stock are transferred from the rail through the brace plates and into the road bed. In an alternative embodiment, wherein a guard rail is mounted within the brace plate parallel to the load carrying rail, the rail fastener assembly further includes a wedge interposed between the brace plates and the guard rail to transfer centrifugal forces from the guard rail thereby maintaining the guard rail, in a vertical orientation. In addition, the wedge affords increased simplicity, and versatility and facilitates track installation.
In the prior art, numerous rail fastener assemblies have been devised for supporting the rails of a railway system. Some of these fasteners are used in conjunction with cross ties while others are of the direct fixation type which may be connected directly to the track bed. In either type construction, the rail track fastener is subjected to relatively high stresses as heavy loads of rolling stock pass along the rails. More specifically, as the rolling stock travels along the rails, the rails and rail fasteners are subjected to repeated poundings causing the rails to flex under the moving loads. In order to alleviate the stresses developed by the rolling stock, resilient rail fastener assemblies have been developed which permit the assembly to flex under stress. An example of a resilient rail track fastener may be found in U.S. Pat. No. 3,945,566 to Bush, and assigned to the same assignee as the subject invention. In the Bush patent, the fastener is provided with an elastomeric pad which is interposed between the rail and the base plate creating a degree of flexibility in the fastener to absorb the stresses induced by the rolling stock.
Another problem associated with rail maintenance, concerns the centrifugal forces imparted to the rail on a curved section of track. More specifically, as rolling stock is guided around a curved portion of the rail, the inertia developed by the rolling stock exerts centrifugal forces directed perpendicular to the longitudinal axis of the rail which tends to cause the rail to bend or shift out of a vertical orientation. These recurring forces placed on the rails by each wheel of the rolling stock, generates vibrations in the rails and the fastener assemblies creating noisy operations. Further, the centrifugal forces on the rail, in combination with the vibrations produced by the rolling stock, tend to cause the connections in the fastener assembly to loosen, necessitating frequent readjustment or repair thus rendering the tracks unstable for safe operations. As can be appreciated, increased noise in urban environments is clearly objectionable, and increased maintenance and down time is equally undesirable.
Certain rail fastener assemblies found in the prior art have been designed to alleviate noise, vibration and the centrifugal forces imparted to the rail. For example, in the above cited patent to Bush, a single brace member, connected to a spring plate, which is in turn bolted to the rail fastener assembly, is provided to inhibit the side motion or overturning of the rail. A similar brace member is disclosed in U.S. Pat. No. 3,819,114, to Bush and assigned to the same assignee as the subject invention. The braces disclosed in the above cited patents are contoured to the shape of the rail, and in addition, are welded to elements which are in turn bolted to the base plate. The bolt connections between brace members and the base plates frequently loosen allowing the braces to shift. These prior art fastener assemblies were effective in reducing the overturning of rails under the force of the rolling stock. However, it is desirable to provide less complex rail track fastener assembly which provides rigid resistance to the centrifugal forces created by the rolling stock, and in addition, simplifies rail replacement and reduces time for such replacement. Further, it is desirable to provide a rail track fastener assembly which includes a wedge means to provide rigid support in a low guarded rail assembly to prevent the guard rail from overturning under the centrifugal forces of the rolling stock.
Accordingly, it is an object of the subject invention to provide a new and improved rail fastener assembly for curved track which provides superior resistance to centrifugal forces imparted to the rail by the rolling stock.
It is a further object of the subject invention to provide a resilient rail fastener assembly which is operative to reduce unwanted noise and vibration.
It is another object of the subject invention to provide a new and improved rail fastener assembly which is simple and facilitates rail installation and replacement.